“If everything slows up and takes longer, at some point in the day you’d need extra trains and drivers to fill gaps.

“ScotRail has some of the best punctuality in Britain. The last thing we want to do is upset customers.”

Last month, 93.6 per cent of its trains arrived within five minutes of schedule - the standard industry measure.

The dispute is part of Britain-wide timetable review by Network Rail, against which some train operators south of the Border are also believed to have appealed.

In Scotland, it comes despite ScotRail and track owner Network Rail forming an alliance in 2015 to work closer together.

The dispute has arisen because the two bodies have been given different performance targets - set before the ScotRail Alliance was created.

This is despite the partnership being established to “enable both to work to common aims and objectives”.

While Network Rail is focused on improving reliability, ScotRail is seeking to reduce journey times.

In a letter to ministers this week, Network Rail chief executive Mark Carne said: “I believe strongly that we must improve timetable accuracy if we are to run the reliability of services that passengers increasingly expect.”

But he said its “key performance indicators” did not include journey time.

A spokeswoman for the Scottish Government’s Transport Scotland agency said: “We have asked Network Rail to work closely with the ScotRail Alliance to identify the best solution to timetabling, with a clear focus on the needs of passengers and the priorities of Scottish ministers in reducing, as opposed to extending, journey times wherever possible.

“Once again, this situation highlights the need for further devolution of Network Rail.”

The official passenger watchdog said travellers wanted both punctual trains and faster journeys.

Transport Focus senior stakeholder manager Robert Samson said: “Our passenger priority research identified that passengers’ want a punctual and reliable railway, with an improved frequency of service and reduced journey times, where possible.

“Any changes to timetables should be focus on those passenger priorities.”